Demand gas flow valve apparatus

Abstract

A breathing circuit system for delivering gas from a fresh source to a user through a face mask. The system includes a cylindrical housing and a resiliently-biased valve supported substantially centrally within the housing. In the default or “off” position, the resilient bias causes the valve to be seated on a valve seat shutting off axial flow of gas through the valve housing. When the patient or user breathes, negative pressure is applied to one side of the valve effective to sufficiently overcome the resilient bias imposed on the valve to move the valve off the valve seat axially (or otherwise open in another direction) within the housing, thereby allowing flow of gas through both the valve seat and the valve housing, and into the breathing circuit connected thereto. When the patient's breathing pauses and begins to exhale, the valve bias returns the valve to its default or off condition shutting off flow of gas through the valve.

What is claimed is: 
     
       1. A breathing circuit system for delivering gas to a user through a face mask, the breathing circuit system comprising:
 an inspiration lumen having a proximal end and a distal end, the proximal end of the inspiration lumen being directly or indirectly coupled to the face mask; 
 a demand valve having a proximal end in fluid communication with the distal end of the inspiration lumen and a distal end in fluid communication with a supply of fresh gas; 
 the demand valve including a closed position and an open position, the closed position being a default position in the absence of negative pressure in the inspiration lumen, such that the gas from the source of fresh gas cannot enter the inspiration lumen through the demand valve, and the open position occurring in the presence of negative pressure in the inspiration lumen, such that fresh gas from the source of fresh gas can enter the inspiration lumen through the demand valve; 
 a flowmeter fluidically coupled between the supply of fresh gas and the demand valve, wherein the flowmeter includes a control panel configured to control the delivery of gas out of the flowmeter; 
 a gas reservoir fluidically coupled between the flowmeter and the demand valve, wherein the gas reservoir is configured to receive fresh gas leaving the flowmeter when the demand valve is in the closed position; 
 a pressure sensor configured to determine if a pressure in the gas reservoir exceeds a predetermined threshold of pressure to prevent over-inflation of the gas reservoir; 
 a conductor electrically coupled to the pressure sensor and to the control panel of the flowmeter, the conductor configured to receive an over-inflation signal from the pressure sensor when the pressure sensor determines that the pressure in the gas reservoir exceeds the predetermined threshold of pressure and transmit a signal to the control panel to reduce the delivery of gas from the flowmeter; 
 wherein the over-inflation signal prevents the pressure in the gas reservoir from exceeding the predetermined threshold when the demand valve is in the closed position. 
 
     
     
       2. The breathing circuit system of  claim 1 , further comprising:
 the demand valve further including a housing extending axially between the proximal end and the distal end of the demand valve, the housing defining an internal passage extending between the distal end and the proximal end of the demand valve, such that fresh gas can pass from the source of fresh gas to the inspiration lumen through the internal passage in the open position; 
 wherein at least a portion of a valve member moves axially within the internal passage, wherein the internal passage being fully obstructed by the valve member in the closed position, thus preventing flow of gas through the internal passage; 
 wherein the internal passage being only partially obstructed by the valve member or not obstructed at all in the open position, thus permitting flow of gas through the internal passage; 
 wherein the resilient bias member maintains the valve member in the closed position as the default position. 
 
     
     
       3. The breathing circuit system of  claim 2 , further comprising:
 the demand valve further including a transverse divider wall disposed within the housing and including a valve seat, the transverse divider wall dividing the housing into a proximal compartment and a distal compartment located respectively on opposite sides of the valve seat, 
 the internal passage including an opening disposed through the transverse divider wall, the valve member fully obstructing the opening in the closed position. 
 
     
     
       4. The breathing circuit system of  claim 3 , further comprising:
 the internal passage further including arcuately-shaped flow passages disposed through the transverse divider wall, the valve member fully obstructing the arcuately-shaped flow passages in the closed position. 
 
     
     
       5. The breathing circuit system of  claim 3 , further comprising:
 the internal passage further including supplemental flow passages disposed through the transverse divider wall, the valve member fully obstructing the supplemental flow passages in the closed position. 
 
     
     
       6. The breathing circuit system of  claim 3 , further comprising:
 the valve member including a piston and a stem extending axially from the piston through the opening from the proximal compartment into the distal compartment, the piston positioned in the proximal compartment directly adjacent to the valve seat in the closed position, 
 the resilient bias member positioned in the distal compartment of the demand valve and causing axial movement of the stem within the opening, wherein the piston engages the valve seat to fully obstruct the internal passage in the closed position. 
 
     
     
       7. The breathing circuit system of  claim 6 , further comprising:
 the resilient bias member being a spiral or compression spring having a first end and a second opposed end, 
 the spring being disposed around the stem with a proximal end of the spring engaging or otherwise disposed adjacent to the transverse divider wall. 
 
     
     
       8. The breathing circuit system of  claim 7 , further comprising:
 the spring comprising sufficient stiffness to withstand external pressure and forces until an activating negative pressure of about −1 cmH 2 O to about −10 cmH 2 O is present within the proximal compartment. 
 
     
     
       9. The breathing circuit system of  claim 6 , further comprising:
 a retainer washer coupled to the stem in proximity to a distal tip of the stem, 
 wherein a proximal end of the resilient bias member engages or is otherwise disposed adjacent to the transverse divider wall, 
 wherein a distal end of the resilient bias member engages or is positioned directly adjacent to the retainer washer, such that the resilient bias member is maintained on its proximal end by the transverse divider wall and on its distal end by the retainer washer. 
 
     
     
       10. The breathing circuit system of  claim 9 , further comprising:
 a sleeve extending distally from the transverse divider wall into the distal compartment, the sleeve surrounding the resilient bias member, 
 wherein the retainer washer contacts the sleeve in the open position to prevent the valve member and the resilient bias member from traversing further proximally when the demand valve transitions from the closed position to the open position. 
 
     
     
       11. The breathing circuit system of  claim 9 , further comprising:
 the stem of the valve member including a pair of tangs, each tang having a barb that defines a retention ledge that is disposed a spaced distance away from the distal tip, the retainer washer coupled to the stem by sitting on the retention ledge of each tang, wherein the barb of each tang is disposed through a central aperture of the retainer washer. 
 
     
     
       12. The breathing circuit system of  claim 6 , further comprising:
 an O-ring positioned between the piston and the valve seat in the closed position. 
 
     
     
       13. The breathing circuit system of  claim 3 , further comprising:
 an axial stop projection extending within the proximal compartment and engaging the valve member, the axial stop projection stopping the valve member from traversing further proximally when the demand valve is transitioning from the closed position to the open position. 
 
     
     
       14. The breathing circuit system of  claim 1 , further comprising:
 the gas delivered to the user being nitrous oxide, oxygen, or a mixture of nitrous oxide and oxygen. 
 
     
     
       15. A method of delivering gas to a patient, the method comprising:
 providing to the patient a breathing circuit system, wherein the breathing circuit system comprises:
 an inspiration lumen having a proximal end and a distal end, the proximal end of the inspiration lumen being directly or indirectly coupled to the face mask; 
 a valve having a proximal end in fluidic communication with the distal end of the inspiration lumen and a distal end in fluid communication with a supply of fresh gas; 
 the valve including a closed position and an open position, the closed position being a default position in the absence of negative pressure in the inspiration lumen, such that gas from the supply of fresh gas cannot enter the inspiration lumen through the demand valve, and the open position occurring in the presence of negative pressure in the inspiration lumen, such that fresh gas from the supple of fresh gas can enter the inspiration lumen through the valve; 
 
 a flowmeter fluidically coupled between the supply of fresh gas and the demand valve, wherein the flowmeter includes a control panel configured to control the delivery of gas out of the flowmeter; 
 a gas reservoir fluidically coupled between the flowmeter and the demand valve, wherein the gas reservoir is configured to receive fresh gas leaving the flowmeter when the demand valve is in the closed position; 
 a pressure sensor configured to determine if a pressure in the gas reservoir exceeds a predetermined threshold of pressure to prevent over-inflation of the gas reservoir; 
 a conductor electrically coupled to the pressure sensor and to the control panel of the flowmeter, the conductor configured to receive an over-inflation signal from the pressure sensor when the pressure sensor determines that the pressure in the gas reservoir exceeds a predetermined threshold of pressure and transmit a signal to the control panel to inactivate the flowmeter; 
 wherein the inactivation of the flowmeter prevents the over-inflation of the breathing circuit when the demand valve is in the closed position.